JPH01274907A - Hammer drill - Google Patents

Abstract

PURPOSE:To save energy consumption by applying the constitution wherein the axial shift of a drill bit is made free for a spindle, a striker is provided in a piston between an impact body free to move in an axial direction and a drill bit, and the striker is connected to a clutch ON/OFF means. CONSTITUTION:When the tip of a drill bit 8 is not on a drilling surface, a striker 33 is at an advanced position and a clutch 6 is in an disengaged condition via the force of a clutch axis 60 due to a spring 64. When a motor 2 is started with the operation of a switch handle 14, therefore, the rotation of the motor 2 is transmitted to the drill bit 8 via a spindle 3. As a motion conversion member 5, however, is disengaged, a piston 4 does not reciprocates and the drill bit 8 only rotates. Also, when the drill bit 8 is pressed to the drilling surface, the clutch 6 is engaged and the piston 4 reciprocates via the member 5. Furthermore, an impact body 41 follows and an impact generated when the impact body 41 hits the striker 33, is transmitted to the drill bit 8.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a hammer drill in which not only rotation but also axial impact impact can be applied to the drill bit.

[Conventional technology]

There is a tool called a hammer drill as a tool for drilling holes in concrete. This includes a striking means that is reciprocated in the axial direction and a striking body that is also slidable in the axial direction, and an air spring is interposed between the two.
The movement of the striking means is transmitted to the striking body via an air spring, and a striking impact is further applied to the drill bit rotationally driven by the striking body. By the way, if the drilling impact is applied to the drill bit even when the drill bit is not pressed against the surface to be drilled, in other words, if dry drilling occurs, damage to various parts will be accelerated. Generally, this type of tool is constructed so that the striking body does not strike the drill bit when the drill bit is not pressed against the surface to be drilled, in order to prevent dry striking. However, since the reciprocating drive of the striking means and the reciprocating movement of the striking body were still being carried out, damage caused by dry striking could be prevented, but even though the work was not actually carried out,
This has the problems of high energy consumption and noise generation. Energy consumption is especially a big problem in devices that use batteries as a power source. To this end, British Published Patent No. 2,170,746 shows the following. This is because a clutch is installed between the striking means and the motor, and when the drill bit is pressed against the surface to be drilled, this clutch is connected, and when the drill bit is released from the surface to be drilled, the clutch is disengaged and the impact is struck. The means are rendered inoperable. In other words, while holding the drill pit ■-, the spindle that transmits the rotational force from the motor to the drill pit 1 is made slidable in the axial direction. 7 and press the drill bit onto the surface to be drilled (
At 17, using the 3M after the spindle, the clutch was connected, and the striking means for applying a striking impact to the drill bit was activated only when the drill bit was pressed against the surface to be drilled. I'm just trying to make it work.

[Problems to be Solved by the Invention] However, with the above structure, since the spindle is movable in the axial direction, concrete damage that occurs during drilling can be avoided.
There is a risk that the fine chips of No. 1 will enter the mechanism and cause field deterioration. The present invention has been developed in view of these points, and its purpose is to automatically disconnect the striking means from the motor when the striking action is not required, thereby reducing energy consumption, and to achieve the above-mentioned advantages. To provide a hammer drill with a structure for automatic separation that does not cause chips to enter into a mechanism part. [Means for Solving the Problems] The present invention provides a spindle which is rotatably driven by a motor and which holds a drill bit, and which is connected to the motor via a motion converting member. The drill bit includes a striking means that reciprocates and applies a striking impact to the drill bit via an air spring and a striking body, and a clutch that is located between the motor and the motion converting member to transmit and control power between the two. In a hammer drill, the drill bit can be freely moved in the axial direction relative to the spindle.
A striker is disposed within the spindle and is movable in the axial direction and interposed between the striking body and the drill bit, and the striker is connected to the on/off means of the clutch. ,ing. [Function] According to the present invention, until the drill bit is pressed against the surface to be drilled, the clutch is released! In D, no power is transmitted to the striking means, and the movement of the drill bit when it is pressed against the surface to be drilled occurs via the spindle. instead of being transmitted to the clutch on/off means,
The power is transmitted via a striker disposed within the spindle and interposed between the striking body and the drill pit. EXAMPLES] The present invention will be described in detail below based on illustrated examples. First, to explain the overall structure, the main body housing 1 has a drill pin at its front end. The chuck part 13 on which the -8 is attached is arranged, and the handle part 16 extends from the lower part of the rear end, and when it is located in front of the handle part 16 at the lower center Jf of 2, the storage battery may run out. It is said to be removable. In the figure, 1-4 is a switch handle, 15 is a rotation direction switching handle, and 12 is a motor mounting base. As shown in FIG. 1, the motor 2 is housed in the rear part of the main body housing 1 with its axial direction being the front-rear direction, and a pinion 21 is fixed to its output shaft 20. This pinion 2] is press-fitted into one end of an intermediate member 23 whose both ends are rotatably supported by the housing 11 and the motor mount 12 via bearings 22, 22, and whose axial direction is the motor 2. Intermediate shaft 2 parallel to the axial direction
It meshes with a reduction gear 24 press-fitted into one end of 3. A motion converting member 5 is attached to one end of the intermediate shaft 23,
A clutch shaft in which a pinion 25 having a long axial dimension is formed on the outer peripheral surface of the other end, and an internal gear 61 that has a cylindrical shape and meshes with the pinion 25 on the inner peripheral surface of one end. 60 is disposed to be slidable in the axial direction, and a cylindrical clutch plate 65 is also disposed on the outer periphery of the clutch shaft 60 to be slidable in the axial direction. The clutch shaft 60 is provided with a flange 63 at its end on the motion conversion member 5 side, and has a plurality of notches 62 cut out from the outer circumference of the flange 63 as shown in FIG.
A clutch plate 65 placed over the clutch shaft 60 is provided with a plurality of clutch pawls 66 that are passed through the notches 62 of the clutch shaft 60 and whose tips protrude toward the motion conversion member 5 side beyond the clutch shaft 60. There is. A spring 64 is disposed between the motion converting member 5 and the clutch shaft 60, and a retaining ring 6 is provided on the clutch shaft 60.
A spring 67 is disposed between the clutch plate 65 and the spring seat 69, and the springs 64 and 67 bias the clutch plate 65 toward the motion conversion member 5, and the clutch shaft 60 is reversely biased. biased in the direction. On the other hand, a spindle 3 rotatably supported by a bearing 30 is installed in the front end of the main body housing 1, which also serves as a gear case. This spindle 3 has a gear 32 that engages with the pinion 25 attached to the outer peripheral surface of the rear end of the spindle 3 so as to be slidable in the axial direction by a key 38, and a striker 33 is installed inside the spindle 3 so that it can be slid in the axial direction. The tip portion constitutes a member of a chuck 13 that holds the drill bit 8 so that it can freely slide within a predetermined range. In the figure, 39 is a mounting groove for the key 38. Here, the striker 33 has its sliding range in the axial direction restricted by a locking body 34 fixed inside the spindle 3, and after its diameter is reduced, the end portion of the spindle 3 is A cup-shaped bushing 35 housed in the rear end is covered with an elastic body 73 such as an O-ring, and the elastic body 73 is positioned between the spindle 3 and the bushing 35 in the axial direction. The bushing 35 is provided with a projection 36 that projects outward from an axial slit 37 formed at the rear end of the spindle 3 and contacts the surface of the gear 32 on the drill bit 8 side. On the other hand, behind the striker 33, there is installed a piston 4 which serves as a striking means and has a cylindrical shape with a bottom, and a striking body 41 which is slidably disposed within the piston 4.The piston 4 is connected to the motor. It is held slidably in a direction parallel to the axial direction of the intermediate shaft 23 and the spindle 3 by a part of the cylinder formed on the motor mount 12 to which the motor 2 is attached, and is connected to the motion converting member 5. The motion conversion member 5 converts rotational motion into reciprocating motion, and includes a cylindrical body 50 into which the intermediate shaft 23 is inserted, and a large number of cylindrical bodies on the outer peripheral surface of this cylindrical body 50. A ring 52 is freely rotatably attached via balls 51, and a shaft 5 protrudes from the ring 52.
3, and a slider 5 which is slidable on the shaft 53 and whose one end is connected to the piston 4 by a piston pin 44.
4, the center axis of rotation of the ring 52 is inclined with respect to the axial direction of the intermediate shaft 23, and when the cylindrical body 50 rotates together with the intermediate shaft 23, the ring 52 protrudes from the ring 52. The shaft 53 swings, and as a result, the piston 4
A reciprocating drive is performed. As described above, the gear 32 provided on the spindle 3 meshes with the binion 25 on the intermediate shaft 23, and the end face of the clutch shaft 60, which is biased by the spring 64, is attached to the thrust plate 27. are in contact through Further, the intermediate shaft 23 in the motion converting member 5
The clutch shaft 60 of the cylinder 50 is freely rotatably attached to the
A concave groove 56 is formed on the side end surface, into which a clutch pawl 66 protruding from the clutch plate 65 engages. When the clutch pawl 66 is not engaged with the groove 56, the motion converting member 5 and the piston 4 are disconnected from the motor 2, but when the clutch pawl 66 is engaged with the groove 56, the motor 2 is disconnected. The rotation of the piston 4 is transmitted through the motion converting member 5.
transmitted to. Between the clutch plate 65 and the motion converting member 5 (this is where the clutch 6 is formed).Furthermore, on the side of the main body housing 1, there is a disconnection lever 70 for forcibly blocking the connection of the clutch 6. A detachment lever 70 rotatably attached to the main body housing 1 has a pin 7 protruding from an eccentric position on its tip surface, and a motion converting member attached to the clutch plate 65. A roller 72 in contact with the end surface on the 5 side is supported reversibly by a pin 71.However, in the lever hammer drill, when the tip of the drill bit 8 is not in contact with the surface to be drilled, the roller 72 in FIGS. As shown, S1 to Leica 33 are in the forward position,
The clutch 6 is in a disengaged state due to the bias of the clutch shaft 60 by the spring 64. Therefore, when the motor 2 is operated by operating the switch handle 14, the rotation of the motor 2 is transmitted from the intermediate shaft 23 to the drill bit 8 via the spindle 3, but since the motion converting member 5 is separated, GS-, bis1-
drill bit 8 without reciprocating
performs only rotation. In this state, if the tip of the drill bit 8 is pressed against the surface to be drilled, G will appear as shown in Figures 5 and 6.
The drill bit 8 is retracted relative to the spindle 3 within the permitted range, pushing the striker 33 rearward and retracting the drill bit. The striker 33 is an elastic body 73.
The gear 32 is moved backward through the pusher 35, and the gear 32 pushes the clutch shaft 60 attached to the intermediate shaft 23 toward the motion conversion member 5 against the spring 64. As a result, the clutch pawl 66 of the clutch plate 65 is rotated by the spring 67.
In a state where it receives the downward force, it engages with the concave groove 56 in the motion converting member 5 and connects the clutch 6. Thereafter, the reciprocating motion of the piston 4 is controlled through the motion conversion member 5, and the striking body 41 follows the reciprocating motion of the piston 4 via the air spring between the inner bottom surface of the piston 4 and the striking body 41. , and the blow when the striking body 41 strikes the striker 33?
! ! i"l is transmitted to the drill bit 8 through the striker 33. The reaction force generated when the striker 33 applies a striking impact to the drill bit 8 is absorbed by the elastic body 73 disposed between the striker 33 and the butcher 35. In addition, since the clutch pawl 66 of the clutch 6 is engaged with the motion conversion member 5 side while being pushed by the spring 67, the connected state of the clutch 6 becomes unstable due to the above-mentioned reaction force. In addition, no sound is generated due to vibration between the striker 33 and the button shear 35. When the drilling operation is completed and the drill bit 8 is released from the surface to be drilled, the clutch is activated by the force of the spring 64. As the shaft 60 separates from the motion converting member 5, the clutch pawl 66 of the clutch plate 65 comes out of the groove 56, the clutch 6 is disengaged, and the gear 32, pusher 35, striker 33, and drill bit 8 also return to their initial state. Returns to position 6 Therefore, the drill bit 8 is in a state where it only rotates.When drilling into iron plates or wood does not need to involve striking, the drill bit 8 can be rotated by rotating the release lever 70. As shown in FIG. 7, the movement of the clutch plate 65 toward the motion converting member 5 may be prevented by a roller 72. In the above embodiment, the striker 33 and the clutch shaft 60, which is the on/off means for the clutch 6, In the embodiment shown in FIG. 8, the gear 32 is fixed to the spindle 3, and the pusher 35 directly moves the clutch shaft 60. In FIG. 8, the upper side of the axis of the intermediate shaft 23 and the lower side of the axis of the spindle 3 are in a state where the clutch 6 is disengaged, and the lower side of the axis of the intermediate shaft 23 and the upper side of the axis of the spindle 3 are in a state where the clutch 6 is connected. [Effects of the Invention] As described above, in the present invention, even when the motor is operated, the striking means performs reciprocating motion when the drill bit is not pressed against the surface to be drilled. The impact means does not start operating until the drill bit is pressed against the surface to be drilled, and as a result, there is no unnecessary energy consumption and noise generation is suppressed. Yes, and in transmitting the fact that the drill bit has been pressed against the surface to be drilled to the clutch on/off means,
The spindle is not a spindle that holds the drill bit, but a striker that is freely slidable in the axial direction and interposed between the striking body and the drill bit, so the spindle is simply left rotatable. Since the spindle is movable in the axial direction, there is no intrusion of fine concrete powder into the mechanism, and a long-life and highly reliable product can be obtained. In addition, in the case where an elastic body is interposed between the striker and the clutch on/off means, the elastic body buffers the reaction force when the striking means applies a striking impact to the drill bit via the striker, and the clutch In order to prevent the above-mentioned reaction force from acting directly on the on/off means side, the clutch connection shape will not become unstable and no abnormal noise will occur.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of the same clutch, Fig. 312 is a perspective view of the clutch shaft and clutch plate of the above, and Fig. 4 is a cross-sectional view of the same above. , FIG. 5 and FIG. 6 are longitudinal sectional views when the clutch is connected, FIG. 7 is a sectional view when the clutch is forcibly disengaged, and FIG. 8 is a longitudinal sectional view of another embodiment. A motor, 3 a spindle, 4 a piston, 5 a motion conversion member, 6 a clutch, 8 a drill bit, 41 a striking body, 60 a clutch shaft, 65 a clutch plate, and 73 an elastic body. Agent Patent Attorney Ishi 1) Chief Figure 7 4

Claims (2)

[Claims] (1) A motor, a spindle that is rotationally driven by the motor and holds the drill bit, and a spindle that is connected to the motor via a motion conversion member to perform reciprocating motion and that is connected to the drill bit via an air spring and a striking body. A hammer drill equipped with a striking means for applying a striking impact and a clutch positioned between a motor and a motion converting member to control power transmission between the two, the drill bit being freely movable in the axial direction with respect to the spindle, A hammer characterized in that a striker is disposed within the spindle and is movable in the axial direction and interposed between the striking body and the drill bit, and the striker is connected to the on/off means of the clutch. Drill. (2) The hammer drill according to claim 1, further comprising an elastic body interposed between the striker and the clutch on/off means.